This disclosure relates to polyetherimides and compositions containing the polyetherimides, as well as their method of manufacture and articles formed from the polyetherimide compositions.
Polyetherimides (“PEIs”) are amorphous, transparent, high performance polymers having a glass transition temperature (“Tg”) of greater than 180° C. Polyetherimides further have high strength, heat resistance, and modulus, and broad chemical resistance, and so are widely used in applications as diverse as automotive, telecommunication, aerospace, electrical/electronics, transportation, and healthcare.
Polyetherimides can be manufactured by polycondensation of a dianhydride with an organic diamine (polycondensation). An ongoing challenge associated with the polycondensation reaction is achieving high conversion of dianhydride and organic diamine to polyetherimide in a commercially useful reaction time. The rate of polycondensation can be increased by conducting the reaction at higher temperatures, but decomposition can occur or unwanted by-products can form. Alternatively, polycondensation can be conducted at a lower temperature in the presence of a catalyst. For example, U.S. Pat. No. 4,324,882 discloses sodium phenylphosphinate (“SPP”) as a useful catalyst for the polycondensation reaction. However, the use of SPP, like the use of higher temperatures, can result in unwanted by-products that can adversely affect the physical properties of the polyetherimide. Moreover, the presence of residual SPP in the polyetherimide can adversely affect the hydrolytic stability of the polyetherimide under certain conditions.
Thus there remains a need in the art for an improved process for the manufacture of polyetherimides that does not result in decomposition or side reactions that can adversely affect the properties of the polyetherimides, for example hydrolytic stability. It would be a further advantage if such methods allowed the production of polyetherimides having reduced branching, as measured by the polydispersity index or by R*, and reduced color, as compared to prior art polyetherimides. A still further advantage would be scalability of the process to industrial production levels. It would also be advantageous if such methods were effective in providing polyetherimides in high yields within a commercially useful reaction time.